In U.S. Pat. No. 4,396,188, issued Aug. 2, 1983, there is illustrated an exercise machine of the rowing type in which the operator rolls back and forth on a seat mounted on a main support beam. On rear movement, the operator pulls on a pull bar attached to a chain, which extends around gears on the wheel axle, rotating the wheel. Resistance to rotation is provided by air paddles mounted on the wheel. The end of the chain opposite to the end attached to the pull bar is attached to a spring, which extends when the chain is pulled. Therefore on the forward return stroke, the extended spring contracts to assist in pulling the pull bar forwardly. Although the sensation provided by the machine on the pulling stroke is similar to that of an actual rowing stroke, the assistance provided by the machine on the forward stroke provides a sensation which is completely different from that of the sensation during the return of an oar during actual rowing, since it pulls the arms and upper body of the operator forwardly, whereas in actual rowing, the rower must push the oar handle forwardly against the resistance of the wind on the oar blade and the friction of the oar lock, which requires a positive forward force to move the oar back to the forward position in preparation for another rowing stroke.